Embodiments of the present invention relate to an eraser system for use with an a display system having a display surface with optical detection elements. In particular, exemplary embodiments relate to an eraser for use with an electronic whiteboard assembly with two or more optical detection elements for determining the coordinates of the eraser relative to its display surface.
Whiteboards are a well-known medium for facilitating the exchange of information by providing a convenient surface upon which notes, drawings, charts, or other notations may be made. As with the traditional chalkboard, whiteboards allow notations to be made in multiple colors and to then be erased. Whiteboards offer several advantages over chalkboards including a clean white surface that provides for greater contrast over the traditional green or black background of chalkboards. In addition, writing on a whiteboard is easier for many than on the traditional chalkboard. For example, the smooth writing surface of the whiteboard allows easy use of the erasable felt tip markers used on whiteboards, whereas the chalkboard surface provides a somewhat scratchy surface to hold the chalk used for writing on such surfaces. In addition, many users prefer a whiteboard to a chalkboard simply because the marker may be gripped easier than chalk and does not mark the user's hand when gripped.
Recently, electronic whiteboards have been developed to allow the user's writings and notations entered upon the display surface of the whiteboard to be electronically captured and transmitted to a computer for storage, display, and manipulation. Such electronic whiteboards allow the images and notations made upon the whiteboard to be saved in the computer, to be displayed, printed, transmitted, or manipulated.
Yet, depending on the methods and devices used in the electronic whiteboard systems for detecting the position of an input device or, for example, an erasing device, some difficulty has been had in accurately detecting the location and orientation of the erasing device. Conventional electronic whiteboard systems provide such erasing devices for erasing digital markings of a pen or stylus, but as noted, erasing devices for such systems come with a number of disadvantages.
Various methods and devices for detecting the position of an input device/erasing device relative to the display surface of an electronic whiteboard have been previously developed. For example, position or pressure sensing input devices using tactile sensors have been employed in conventional electronic whiteboard systems. These conventional approaches, however, often are complex, difficult, or expensive to manufacture, and/or have limited performance, especially for large area input device applications. Camera-based systems are also known. Yet, eraser devices useful with camera-based systems are typically circular, to overcome orientation identification issues.
Rectangular erasers are traditionally provided for conventional non-electronic whiteboards, and are beneficial because they allow a user to erase either a large swath or a smaller portion with a single stroke, depending on how the eraser is oriented in the plane of the whiteboard surface. On the other hand, electronic whiteboard systems generally implement circular erasers. Rectangular erasers, while beneficial, require the electronic whiteboard system to determine the orientation as well as the placement of the eraser, as the area of erasure depends on both these variables. In contrast, orientation of a circular eraser is irrelevant because a circle covers the same space regardless of orientation. The user of an electronic whiteboard system with a circular eraser, however, may not be able to vary the size of the area erased in a single stroke. These circular erasers are large enough to erase the board easily, but may be unable to erase a single word, or are small enough to erase a word, but take an immense amount of effort to erase a large board.
With electronic whiteboard systems with optical detection elements, or camera-based systems, it is difficult to judge the orientation of a conventional rectangular eraser. For example, FIGS. 1A-1B illustrate that it is difficult to ascertain if the eraser is horizontally (position A) or vertically (position B) oriented. Such a two-potential-orientation-state eraser, identified herein as “eraser ghosting,” is problematic, as proper erasure cannot be determined with definiteness. Each of the two eraser orientations presents two different user-intended erasure areas.
While conventional electronic whiteboard designs increase the versatility and useability of the traditional whiteboard, a need continues to exist for an electronic whiteboard with improved means for detecting input on the display surface from a user, associating the input with an image displayed on the whiteboard, and improved means for detecting an erasing device for accurate erasure of such inputs from the display surface. The embodiments described below are directed to these and other improvements over conventional systems, and namely to a rectangular eraser designed to be used with an optical electronic whiteboard, which can provide the system with accurate orientation information.